private void Merge(BTree234Node <T> root, int index)
{
BTree234Node <T> left = root.children[index];
BTree234Node <T> right = root.children[index + 1];
left.values[1] = root.values[index];
left.values[2] = right.values[0];
if (left.children[0] != null)
{
left.children[2] = right.children[0];
left.children[3] = right.children[1];
}
root.count--;
for (int i = index; i < root.count; i++)
{
root.values[i] = root.values[i + 1];
}
root.values[root.count] = default(T);
for (int i = index + 1; i <= root.count; i++)
{
root.children[i] = root.children[i + 1];
}
root.children[root.count + 1] = null;
left.count = 3;
if (root.count == 0)
{
this.root = left;
}
}
private BTree234Node <T> Split(BTree234Node <T> root)
{
BTree234Node <T> sibling = new BTree234Node <T>();
sibling.count = 1;
root.count = 1;
sibling.values[0] = root.values[2];
root.values[2] = default(T);
if (root.children[0] != null)
{
sibling.children[0] = root.children[2];
sibling.children[0].parent = sibling;
sibling.children[1] = root.children[3];
sibling.children[1].parent = sibling;
root.children[2] = null;
root.children[3] = null;
}
if (root.parent == null)
{
BTree234Node <T> parent = new BTree234Node <T>();
parent.children[0] = root;
parent.children[1] = sibling;
parent.values[0] = root.values[1];
root.values[1] = default(T);
root.parent = parent;
sibling.parent = parent;
parent.count = 1;
this.root = parent;
}
else
{
for (int i = 0; i < root.parent.count + 1; i++)
{
if (root.parent.children[i] == root)
{
for (int j = root.parent.count; j > i; j--)
{
root.parent.children[j + 1] = root.parent.children[j];
root.parent.values[j] = root.parent.values[j - 1];
}
root.parent.children[i + 1] = sibling;
root.parent.values[i] = root.values[1];
sibling.parent = root.parent;
root.values[1] = default(T);
root.parent.count++;
break;
}
}
}
return(root.parent);
}
public void Insert(T item)
{
if (root == null)
{
root = new BTree234Node <T>();
root.values[0] = item;
root.count = 1;
}
else
{
Insert(item, root);
}
}
private string InOrder(BTree234Node <T> root)
{
if (root == null)
{
return("");
}
string output = "";
for (int i = 0; i < root.count; i++)
{
output += InOrder(root.children[i]) + root.values[i] + " ";
}
return(output + InOrder(root.children[root.count]));
}
public void Delete(T item)
{
if (root != null)
{
if (root.children[0] == null && root.count == 1 && root.values[0].CompareTo(item) == 0)
{
root = null;
}
else
{
Delete(item, root);
}
}
}
private void GrowNode(BTree234Node <T> root, int index)
{
BTree234Node <T> child = root.children[index];
if (index > 0 && root.children[index - 1].count > 1)
{
BTree234Node <T> sibling = root.children[index - 1];
child.values[1] = child.values[0];
child.values[0] = root.values[index - 1];
root.values[index - 1] = sibling.values[sibling.count - 1];
sibling.values[sibling.count - 1] = default(T);
child.children[2] = child.children[1];
child.children[1] = child.children[0];
child.children[0] = sibling.children[sibling.count];
sibling.children[sibling.count] = null;
sibling.count--;
child.count++;
}
else if (index < root.count - 1 && root.children[index + 1].count > 1)
{
BTree234Node <T> sibling = root.children[index + 1];
child.values[1] = root.values[index];
root.values[index] = sibling.values[0];
for (int i = 0; i < sibling.count - 1; i++)
{
sibling.values[i] = sibling.values[i + 1];
}
sibling.values[sibling.count - 1] = default(T);
child.children[2] = sibling.children[0];
for (int i = 0; i < sibling.count - 1; i++)
{
sibling.children[i] = sibling.children[i + 1];
}
sibling.children[sibling.count] = null;
sibling.count--;
child.count++;
}
else
{
if (index != root.count)
{
Merge(root, index);
}
else
{
Merge(root, index - 1);
}
}
}
private void Insert(T item, BTree234Node <T> root)
{
if (root.count >= 3)
{
root = Split(root);
}
if (root.children[0] != null)
{
for (int i = 0; i < root.count; i++)
{
if (item.CompareTo(root.values[i]) < 0)
{
Insert(item, root.children[i]);
return;
}
else if (item.CompareTo(root.values[i]) == 0)
{
return;
}
}
Insert(item, root.children[root.count]);
}
else
{
for (int i = 0; i < root.count; i++)
{
if (item.CompareTo(root.values[i]) < 0)
{
for (int j = root.count; j > i; j--)
{
root.values[j] = root.values[j - 1];
}
root.values[i] = item;
root.count++;
return;
}
else if (item.CompareTo(root.values[i]) == 0)
{
return;
}
}
root.values[root.count] = item;
root.count++;
}
}
private bool Find(T item, BTree234Node <T> root)
{
if (root == null)
{
return(false);
}
for (int i = 0; i < root.count; i++)
{
if (item.CompareTo(root.values[i]) == 0)
{
return(true);
}
if (item.CompareTo(root.values[i]) < 0)
{
return(Find(item, root.children[i]));
}
}
return(Find(item, root.children[root.count]));
}
private void DeleteNode(BTree234Node <T> root, int index)
{
if (root.children[0] == null)
{
root.count--;
for (int i = index; i < root.count; i++)
{
root.values[i] = root.values[i + 1];
}
root.values[root.count] = default(T);
}
else if (root.children[index].count > 1)
{
BTree234Node <T> child = root.children[index];
while (child.children[0] != null)
{
Console.WriteLine(child.children[child.count]);
child = child.children[child.count];
Console.WriteLine(child.values[child.count - 1]);
}
root.values[index] = child.values[child.count - 1];
DeleteNode(child, child.count - 1);
}
else if (root.children[index + 1].count > 1)
{
BTree234Node <T> child = root.children[index + 1];
while (child.children[0] != null)
{
child = child.children[0];
}
root.values[index] = child.values[0];
DeleteNode(child, 0);
}
else
{
Merge(root, index);
DeleteNode(root.children[index], 1);
}
}
private void Delete(T item, BTree234Node <T> root)
{
if (root == null)
{
return;
}
for (int i = 0; i <= root.count; i++)
{
if (i < root.count && item.CompareTo(root.values[i]) == 0)
{
DeleteNode(root, i);
return;
}
else if (i == root.count || item.CompareTo(root.values[i]) < 0)
{
if (root.children[0] != null && root.children[i].count == 1)
{
GrowNode(root, i);
}
Delete(item, root.children[i]);
return;
}
}
}
